Pneumatic rock drill



Patented May 5, 1931 i i PATENT or-Fica y arrogant SMITH, or ivronnsro,CALIFORNIA PNEUMATIC Roc-K DRILL Application med August 14, 1924. serialNo. 732,123.

This invention relates to pneumatic Ydrills and hammers in general andmore particularly to a rock drill in which t-he drilling is accomplishedby successive blows upon the drill steel and the steel is also given arotary motion between striking impacts against the rock. Y

T he principal objects of my improvements are to overcome some of thewell known faults of prior drills of this class in providing:

A-Automatic means for instantly reducing rthe force of the blow upon thetool upon entering soft earth or a pocket inthe rock, thus avoidingdestructive blows against the parts when not opposed bythe resistance ofthe rock.

vB--A manual or automatic control for reducing the force of the workingblow with- 90 out affecting other operations of the mechanism. n

C A simplified rotating drive for giving the drill steel a fractionalturn, operative upon either stroke of the piston.

D-A manual-control to stop the rotation without affecting the drillingoperations.

EvAn improved arrangement for blowing out the drill hole throughv thewater line.

F-An improved method of packing the water tube Within the anvil block.

'30 G-An yimproved method of packing the Vanvil housing. y

H-An improved piston construction whereby various weights of piston maybe n used as the work may require, yet without affecting the cut-offrelation of the parts.

I-Minor constructional improvements which will appear as the descriptionproceeds.

Y I attain the objects mentioned by the pneumatic drill constructionshown in the accompanying drawings and in which Figure 1 isalongitudinal section through the operating mechanism showing all of theimportant fea tures, and Figure 2 is a cross Section of Figure l takenalong the line 2 2. Flgure 3 shows in enlarged section my special ring`packing. Figurei isa sectional view of avalve employed in my deviceshowing its relation to certain passageways. f Before entering adetailed description of the mechanism, attention is called to the factthat the assemblage consists essentially of a main cylinder in the axialline of the drill steel or tool having the usual reciprocating piston orhammer within it for delivering successive blows to the tool, and of aplurality of other cylinders, with pistons or valves therein forcontrolling the .operation of the mechanism and also for rotatingthetool.

These auxiliary cylinders and valves are Y in practice positioned aroundthe main cylinder in a way to facilitate construction and assemblage ofthe mechanism, also to provide for the most direct running 'of thevarious passages and for coring them in the solid metal of the body toavoid exposed piping as much as possible. Y

In the drawing, however, the relation of the parts mentioned has beenaltered, the proportions of the walls changed, also the run of ports, soas to bring the various features into one comprehensive cooperatingassemblage and avoid reference tov many sectional views in additionaldrawings. Y i f In the figures, (l) is the body of the machinecomprising several sections all held together-by the usual clampingbolts extending through suitable flanges (2) and engaging the headWithin the body is the main cylinder (4) with a reciprocating piston (5)therein` i Y l Axially extending from the body is the drill steel ortool (6) which may be lugged as shown at (7) or not. Y

The tool ishere shown as having a hollow shank aligned over a. watertube (8) extending from the head through the piston andi passing throughan anvil block (9) which is slidable on the tube and which block isslidable Wit-hin the anvil housing (10). Y

The tube is packed within the anvil block by means of a special silkring packing (11) forced through the tapered recess (l2) to-a slightlyenlargedl recess (13), but the piston is slidable on the tube withoutany packing.-

'Ihe anvil has a shoulder (14)` lto limit its inward'sliding and inoperation of the. drill is held vtightly against this shoulder by theendwise pressure of the tool which rests upon it as shown. This anvilalso functions as an automatic valve to prevent a blow being dcliveredto the tool if the latter finds no resistance aga-inst the rock onaccount of penetrating a pocket therein or of entering soft earth, forin either case the pressure of the tool upon the anvil is reducedwhereupon the anvil is forced outward by the operating air and trips apremature exhaust on the striking blow as will later be described.

The main piston or hammer (5) is a plain steel cylinder adapted to coverand uncover the air ports for automatic reciproca-tion and has a centralchamber filled with wood (15) or lighter metal so as to provide forinterchange of similar length pistons with larger or smaller wool lilledchambers (15') and whereby the weight of tl e piston can be suit ed tothe work with out altering the relation of the air ports to the pistonslength. The Wood filler has also been found a valuable oil retainer toinsure permanent lubrication of the water tube (8).

The reciprocation of the piston (5) is controlled by the distributingvalve which alternatelyT admits air under pressure from the main inletport (16) to the ports (17) and (18) extending respectivelyT to oppositeends of the piston, and which ports alternately act as exhausts fortheir respective ends by communicating through the recessed valve with acommon exhaust port (19).

It should be here noted that the various` air passages are cored in themetal of the body and unless shown as connecing at intersecting pointsthey are in different planes so as to pass each other and lead to theirvarious destinations without interference.

The valve (.15) is itself tripped back and forth by the uncovering bythe piston of small ports (20) and (21) which convey some of the activepressure fluid to the ends of the valve somewhat before the end of thestroke of the hammer piston in either direction.

Upon the inward or return stroke of the piston (5) the air reactsagainst the anvil housing (10) as well as the end of the anvil block (9)held back by the drill tool through pressure of the tool end against therock being drilled, but in case of striking pocket .initherocln orif forany other reason the pressure of the tool against the anvil is rellieved, the anvil is at once forced outwardv by the air pressure actingagainst its inner end, carrying the tool with 1t and bringing the bypass duct into registry with the automatic hammer blow control valvepassage (23) which results in instantly reducing the force of the blowof the hammer piston (5) so that it will not strike with fnllforceagainst an inoperative tool te batter its lugs or destroy the mechanism7but will keep up a gentle blow in soft material.

This is accomplished by a small piston valve (24) normally forced awayfrom the head (3) by a spring (25) to close oil an auxiliary reversevalve tripping port (26) which communicates with the valve trippingpassage (21).

rlhis small valve (24) is displaced by active air pressure from the bypass through the passa-ge (27) upon relief of the tool pressure on theanvil and opens auxiliary reversing port (26) so that the force of thehammer blow of piston (5) is diminished at about the first third of itstravel and this condition is maintained until the pressure on thedrilling tool is restored.

A check valve (28) is placed in passage (27) and a slow leak at (29) topermit return of valve (24) upon reestablishing normal drillingconditions.

The shock of distributing valve (15) is broken largely through confinedair by proper design of portareas and further 'by metal plates (30)backed by live rubber disks (31).

ln addition to the main cylinder exhausting alternately through itsintake ports as eX- plained, an additional or final exhaust is providedat (32) uncovered at either end of complete stroke.

lVhen drilling in material not requiring the maximum blo v, the airpressure inlet (18) for the striking blow may be independently throttledto any predetermined degree by means of a thumb control button actuating spring released plunger (34) which closes olf the inlet passage(18) to an amountdepending on the threaded adjustment of the plungerwith respect to the button which adjustment is permitted by the slottedend of the threaded member as shown at (35), thus by a simple pressureof th-e thumb the force of the blow is instantly reduced.

rlhe water tube receives its supply through the passage (36) from hose(37) controlled by valve (38) and the drill may be blown with air by asimple pressure of thumb piece (39) which moves the spring returnedplunger valve (40) and opens the by pass duct (41) to the main air inlet(16) so that the air can pass directly to the water tube. The main airhose is indicated at (42) with main valve at (e3).

VEhe wat-er tube 8) is sea-led in the head (3) and ported to passage bysuitable packing and glands in any suitable manner a s indicated.

Intermittent partial rotation of the drill tool is effected throughmeans of a ratchet and pawl arrangement similar to the one described inmy former Patent No. 1,284,804, with the exception that thereciprocating wedge (44;) is operated by an air piston (115) which isthrown outward at each inward movement of the main piston (5)- by airreceived at the same time through a passage (e6) connecting vith airinlet (17). Gr if desired the rotation may be effected at the outwardstroke of the piston by throwing the two way valve (69) return eected byspring (50) surrounding the piston rod (5l) and reacting against thebody (1). At the return stroke the air exhausts to the main cylinderthrough port (52) uncovered by the main piston (5) at the end n of itsinward travel and thence through the passages (17) and (32), and the airabove the piston escapes to a certain extent through the joints aroundthe Wedge operating mechanisni thereby diffusing oil throughout, Whilethe remainder is entrapped as a cushion until scavenged by uncovering ofport (53) by the main piston (5).

The piston (45) is also filled With a block of Wood (45') so that it maystill have length and area yet be light in Weight.

Rotary movement is transmitted to the tool (6) through its lugs (7)engaging slots (54) in retaining nut (55) screwed into the revolvableratchet hub (56) having ratchet teeth (57) engaged by paivl (58) pivotedto sliding paWl block (59) and forced toward the teeth by springs (60),the paWl block being moved by the piston Wedge (44) to advance the paivlblock against spring (6l) at each .stroke of the piston (45)substantially as described in my former patent inentione-d.

To avoid displacement or binding of piston rod (5l) through Wear of theWedge (44) or block (59) a locking though sliding joint (62) is providedto connect the piston rod to the Wedge.

By the arrangement shown it Will be seen that the rotation of the tooltakes place only before the blow of piston (5) and that the tool isstationary at the moment of the blow of the piston.

At any time that it is desired to drill With out rotation of the tool, apressure of the finger on the push button (63) projects the end of itWithin the cylinder (49) and stops the piston. t should be observed thatthis button (63) is at a portion of the cylinder circumference to avoidcut off slot (46).

In operation should the tool break through and allow the anvil to moveforward upon the impact of piston (5), the bloW is arrested by a steelring (64) supported against one of my special silk packing rings (65) Asimilar packing' ringis placed at (66) to seal the anvil housing (l0)against the revolvable ratchet hub (56). This packing Was devisedespecially for this purpose Where a seal must be maintained and thematerial must not compress and become dead when subjected to the forceof an occasional Wild blow` When the tool breaks through.

Figure 3 is an enlarged section of the pack ing rings and shows them asmade of silk threads Wound around (on a mandrel) in layers slightlycrossing one another as shown at (67) to form a ring, then Winding orsewing other silk threads through the opening of the ring and over theouter sides as shown at (68) to tie them all together.` These specialsilk rings are soaked in oil before placing in position in the machine,ring (13) being forced into place With a special tool.

Having thus described in detail my improved rock drill it Will be seento possess valuable features useful also in similar tools such as airhammersand the like, especially the automatic reduction of the strikingblow upon reducing endvvise pressure of the tool upon the work, andWhile I show this accomplished by displacement of an anvil block wherebyVthe reversing valve is prematurely tripped by air pressure, it ismanifest that this may be carried out by quite a number of artifices andany arrangement Which will produce this result falling within the spiritof my, invention is sought to be covered in my appended claims.

I claim: i

l. In a pneumatic rock drill, a cylinder, a piston movable therein,means forautomatically admitting fluid under pressure into the ends ofsaid cylinder for reciprocating the piston, auxiliary means forreversing the movement of the piston when the latter has covered only aportion of its stroke, and tool controlled means for making operativesaid auxiliary means upon excessive outward movement of the tool.

2. In a pneumatic rock drill, a cylinder, a piston movabletherein, meansfor automatically admitting luid under pressure into the ends of saidcylinder for reciprocating the piston, auxiliary iiuid operated meansfor reversing the movement of the piston when the latter has coveredonly a portion of its stroke, av tool, and tool controlled means formaking operative said auxiliary means upon excessive outward movement ofthe tool, said L tool controlled means comprising an anvil block movablydisposed between the piston and the tool and having a fluid passagewayplacing the fluid in the cylinder in communication ivith the pistonreversing means when the anvil is moved to a predetermined position. Y

3. In a pneumatic rock drill, a cylinder, a piston movable therein,means for automatically admitting iiuid under pressure into the ends ofsaid cylinder for reciprocating the piston, auxiliary means forreversing the movement of the piston when the latter has covered only aportion of its stroke, and tool controlled means for making operativesaid auxiliary means upon excessive outward movement of the tool, saidauxiliary means comprising an auxiliary valve actuated when the toolcontrolled means is actuated, said auxiliary valve when actuated causingsaid first named means to cut off the fluid to the piston on its powerstroke during the initial movement ot' the piston Jfor diminishingr theforce oi' its blow.

4. A pneumatic rock drill comprising a cylinder, a piston movabletherein, said cylinder having fluid passages for admitting fluid underpressure for reciprocating` the piston, a valve for alternatelyadmitting; fluid to the ends ot' the cylinder, an auxiliary valve foradmitting Huid to the {ii-st valve for actuating it after the piston hascovered only a portion of its strolm said irst valve. when thus actuatedadmitting' fluid to the piston for reversing;` its movement, whereby thepiston will delivei1 a light stroke to a tool.

5. A pneumatic rock drill comprising' a cylinder, a piston movabletherein, said cylinder having iuid passages for admitting; fluid underpressure for reciproating; the pistonv` a valve for alternatelyadmitting fluid to the ends of the cylinder, an auxiliary valve foradmitting fluid to the first valve 'for actuating it after the pistonhas covered only a portion or' its stroke, said first valve when thusactuated admitting fluid to the piston 'for reversing` its movement,whereby the piston will deliver' a light stroke to a tool, and toolcontrolled means for operating said auxiliary valve.

MICHAEL SMITH.

